Grinding machine with automatic feed crush dressing roll



May 10, 1949. L. F. POLK 2,469,988

GRINDING MACHINE WITH AUTOMATIC FEED CRUSH DRESSING ROLL Filed June 4, 1945 2 Sheets-Sheet l INVENTOR Z t4v Z ATTORNEY May 10, 1949. L F POLK 2,469,988

GRINDING MAc'HIfiE WITH AUTOMATIC FEED CRUSH DRESSING ROLL Filed June 4, 1945 2 Sheets-Sheet 2 x, If

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ATTORNEY Patented May 10, 1949 GRINDING MACHINE WITH AUTOMATIC FEED CRUSH DRESSING ROLL Louis F. Polk, Dayton, Ohio, assignor to The Sheffield Corporation, Dayton, Ohio, a corporation of Ohio Application June 4, 1945, Serial No. 597,425

8 Claims. 1

This invention relates to grinding machines, and more particularly to means for truing or surfacing the grinding wheels of such machines.

One object of the invention is the provision, in a grinding machine, of a grindin wheel truing crusher having a motor operated feed to provide a regular or uniform speed of movement of the crusher during the actual forming operation, with supporting and adjusting means for the crusher so that the latter can be manually moved from a position comparatively remote from the grinding wheel to a position in which the crusher is in peripheral contact with the wheel.

Another object of the invention is the provision of a grinding wheel truin device including a rotatable crusher adapted to operate in peripheral contact with the grinding wheel to true the surface of the wheel, and crusher operating and adjustable mechanism including motor driven mechanism for positively feeding the crusher during the actual truing operation together with a manually adjustable carrier by means of which the crusher can be readily and quickly moved into a predetermined starting position, the construction permitting the manual adjustment of the crusher at the start of the crushin operation into exactly the same position that the crusher had at the end of the previous crushing operation.

Another object is the provision of a wheel truing device of the character mentioned, in which a manually operable switch initiates the slow speed drive of the grinding wheel and initiates the operation of the motor driven mechanism by which the crusher is fed toward the grinding wheel axis, there being provision for insuring continuation of the grinding wheel rotation after the motor driven adjusting mechanism has stopped.

\ Otherobjects and advantages of the invention Referring more particularly to the drawing, in which like parts are designated by the same reference numerals in the several views, I0 designates a portion of a grinding machine structure, providing a suitable power drive such as the electric motor H, diagrammatically shown in Fig. 2, which operates the grinding wheel l2 at a comparatively high speed in the grinding operation. The grinding wheel may be used to impart a desired form or shape to work pieces, and in the particular form of grinding machine herein illustrated, the workpieces can be carried by centers, one of which is shown at 13 on the tail stock l4.

Mounted on the frame structure III by means of suitable bolts I5 is a bracket l6 forming a support for a vertically adjustable slide l1. Normally this slide IT is in a raised position as shown in Fig. 1, so that the crusher supporting mechanism that is carried by the slide is positioned rather remotely from the grinding wheel. In this raised position of the parts, the grinding wheel may be covered or shielded by a readily removable cover plate l9 which can be easily taken off when the surface of the grinding wheel is to be trued or formed.

The slide i1 forms a support for a crusher holder 20. This carries a freely rotatable crusher wheel 2|, the surface of which is so formed as to be complementary to the surface formation desired on the grinding wheel. While this shape may take many forms, as herein illustrated the crusher is provided with annular grooves and ridges so that correspondingly shaped grooves and ridges will be applied to the grinding wheel when the crusher and grinding wheel are rotated in peripheral contact with each other, with suitable pressure applied between them. The crusher 2| is mounted for rotation on anti-friction bearings 23 arranged on an arbor 24, which is supported at its opposite ends on holder 20.

The crusher holder 20 has a bearing surface 25 in which an adjusting shaft 25 is rotatably mounted. The lower end of this shaft is threaded and engages a nut 21 which is secured by a lookin pin 28 to the slide I1. When the slide I1 is raised or lowered, it produces corresponding raising or lowering movements of the shaft 26 and consequently similar movements of the entire holder 2!], guides 29 in the supporting bracket is controlling the position of the holder during this raising and lowering movement. By rotating the shaft 26, it will be apparent that the holder 20 can be adjusted upwardly or downwardly with respect to the slide l1.

Rotatably supported in the bracket I6 is a manually operable shaft 3| which can be adjusted by hand wheel 32. Fixed on the shaft 3| is a spur gear 33, the teeth of which mesh with a rack 34 fixed on the slide I1. When this slide is in its lowered position the bottom of the slide contacts with the rests on an adjustable stop 35 held in a suitable predetermined position by a lock nut 36. By turning the hand wheel 32 in a clockwise direction as viewed in Figs. 3 and 4, the rack 34 and the slide H may be moved upwardly. Before adjusting the position of the slide 11, however, a lock that normally secures the slide in its raised or lowered position must be released. This lock comprises a bolt 31 having a locking tooth 38, which fits over the top of the rack 34 when the slide I1 is in its lowermost position, thus holding slide ll firmly to the bracket 16 in the position of the parts as shown in Fig. 4. A spring 39 holds the bolt 31 in locking position. The upper side of the bolt has a transverse groove 49 receiving an eccentric stud 4! on a shaft 42 which is rotatably mounted on the support bracket l6. The end of this stud projects from the side of the bracket I6 and has a hand lever 43 fixed to it, the center axis of the shaft 42 lying below the eccentric stud 4|. Thus by swinging hand lever 43 in a clockwise direction as viewed in Figs. 1 and 4, the eccentric stud 4| is moved to the right and the spring pressed bolt 31 is retracted from the rack 34, permitting operation of the hand wheel 32 to raise the slide 47. The raised position of the carriage can be maintained by swinging the hand lever 43 counter-clockwise again to the position shown in Fig. 1, thus causing the locking tooth 38 to engage the teeth of the rack 34.

A small electric motor 44 is mounted on the upper portion of the holder 20. Its shaft is mechanically connected by suitable speed reducing drive gears to a vertical shaft 45. Fixed on this shaft 45 is a drive disc 46 having wedge shaped notches 41 that receives rollers 48, the disc and the rollers forming a one-way drive between the shaft 26 and the flanged wheel 49, causing counter-clockwise rotation of the wheel 49 when the motor is operating since the rollers 48 are wedged in the notches 41 when the disc 46 rotates in this direction. The flanged wheel 49 is provided with gear teeth meshing with a gear 59 fixed to the shaft 26 so that the latter can be rotated in a clockwise direction as viewed in Fig. 3 by means of the motor 44. Under these conditions, the holder 29 will be gradually lowered at a uniform rate of speed so as to cause the axis of the crusher to approach the axis of the grinding wheel. The shaft 26 is also adapted for manual adjustment, and for this purpose its upper end is provided with a hand wheel so the shaft can be turned in either direction. When it is manually turned clockwise as viewed in Fig. 3, the one-way clutch provided by the rollers 48 is released and the flanged wheel 49 can be rotated in a clockwise direction. The reverse operation of the wheel 49 can take place under the manual control of the hand wheel 5| by releasing rollers 48 from their wedging engagement between wheel 49 and disc 46, releasing levers 52 being provided for this purpose.

Fig. 2 shows the electrical connections that may be used for the control of the motor 44 and the auxiliary motor 54 which has a drive connection with the grinding wheel I! so as to turn the latter at a comparatively slow speed during the crushing operation, as the main drive motor II that drives the grinding wheel during normal grinding operation turns the wheel too fast for satisfactory crushing or forming of the grinding wheel. As shown in Fig. 2, the power supply lines 55 are connected to a coolant pump motor 56 that supplies a coolant fiuid through the supply pipe 53 during grinding or during crushing. The supply lines are connected through a drum switch shown at 5! which can be adjusted from normal driving position in which power is supplied to the main driving motor H to crushing position, in which the transformer 58 is energized and power is supplied to the switches 59 and 60 that control the wheel driving motor 54 and the adjust ing motor 4. The secondary of the transformer is connected to a starting switch 6| which energizes a timing motor 62. The shaft of that motor carries a cam 63 that closes and holds a circuit across the motor after starting switch 6| is released. The shaft of this motor also carries two other cams 64 and which automatically operate switches 66 and 61 respectively, these switches each being in series with a switch controlling relay as indicated at 59r and 691'. When the relay 591' is energized. it closes the switch 59 and when the relay 691' is energized it closes the switch '60. After a predetermined rotation of the shaft of motor 62 the cams 64 and 65 sequentially operate their respective relays to first deenergize motor 44 so the continued feed movements of the crusher holder cease and then de-energize the motor 54 after about two or three turns of the grinding wheel so as to stop the slow speed rotation of the grinding wheel some little time after the feeding movements of the crusher have been stopped. This insures an even and controlled circular form on the grinding wheel as a result of the crusher operation. The cams 64 and 65 are preferably of an adjustable character so the time during which the feeding movements of motor 44 takes place and the time interval during which the grinding wheel continues to rotate at slow speed after the crusher feed stops are readily controllable. For example the cams may be formed of a series of plate sections secured together and capable of relative annular adjustment to vary the length of the cam projection as shown in Fig. 5 in which the cam 64 has been shown.

The holder 29 is normally in its raised position, the crusher being spaced some distance above the grinding wheel and the cover l9 of the grinding wheel is in place below the crusher. When a crushing operation is to take place, the operator first removes the cover plate 19 and swings the drum control switch 51 to a vertical or neutral position, thus deenergizing the high speed driving motor I I Then he swings the hand lever 43 clockwise to retract the locking bolt from the rack. This then permits him to turn the hand wheel 32 counter-clockwise and lower the carriage I! so as to bring the crusher closer to or in contact wiLh the grinding wheel. In this way he lowers the slide II until it is in full contact with stop 35 and he then swings the locking bolt back into engagement with the top of the rack as indicated in Fig. 4, holding the slide l1 securely in this position. In the set up for the first crushing operation on a wheel, there may be some space between the crusher and the grinding wheel when the slide I1 is on the stop, so that his next operation is to turn the hand wheel 5|, and manually lower the holder 20 on the slide 11. In this way he brings the crusher into crushing engagement with the grinding wheel and he can see that he gets driving contact between these two wheels by turning the grinding wheel by hand and noting that the crusher is then rotating. At this time neither the grinding wheel nor the crusher are power driven. He then presses the starting switch 6| and promptly after the timing motor 62 is energized as a result of this operation, the holding circuit is completed through the timing motor and the cams G4 and 65 automatically close circuits through the relays and energize the switches for the grinding wheel driving motor 5 and the crusher feed motor 44. The grinding wheel is thus caused to rotate at comparatively slow speed, while the adjusting motor 44 causes the shaft 26 to be slowly rotated at a uniform rate of speed thus very gradually lowering the crusher toward the grinding Wheel and maintaining pressure engagement between the crusher and the grinding wheel. The rate of lowering movement is quite slow as the reduction gearing between motor 44 and shaft 26 is such that undue pressure that might break the grinding wheel is not applied by the crusher. However by maintaining the down feed of the crusher at an even or uniform rate slow enough to avoid applying breaking force to the grinding wheel, the surface of the grinding wheel will be gradually crushed off and the exact complement of the shape of the crusher will thus be imparted to the periphery of the grinding wheel.

The cams 84 and 65 are so arranged that they will automatically stop the down feed after a desired predetermined time interval adequate to give the required truing action, or, if desired, a stop switch 10 which is normally closed, may be depressed to stop the timing motor and deenergize the relays controlling the motors 44 and 54.

Under normal conditions, however, the truing operation is continued until the switches 64 and 65 are opened one after the other, sequentially deenergizing first the motor 44 and then motor 54. The operator then retracts the locking bolt 31 by swinging the hand lever 43. Then he turns the hand wheel 32 to raise the slide l1, elevating the holder so the crusher is moved away from the grinding wheel to its normal raised position. This does not disturb the position of the holder 20 on slide I! so the next time he has occasion to true the grinding wheel and lowers the slide i! into engagement with stop 35, this will bring the crusher to a position in which it is substantially in contact with the grinding wheel and he is not required to further adjust the hand wheel 5| unless the grinding wheel has been so worn that a pressure engagement between the crusher and grinding wheel does not obtain.

To show the operator how much feed movement is given to the crusher in a crushing operation, and to permit him to exactly control the amount of movement given to the crusher in any operation as may be required, the shaft 26 is provided with an indicator disc 12, having index markings or graduations 13 that can be read in conjunction with a zero line 14 on a fixed part of the holder as shown in Fig. 1.

In accordance with the present invention it is apparent that a comparatively simple control mechanism is provided for giving a positive controlled feed to the crusher, avoiding variations in crushing pressure that would result if the down feed of the crusher during the crushing operation were entirely under the manual control of the operator. Variations in crushing pressure are productive of destructive forces on the grinding wheel, breaking away pieces of the wheel to a considerable extent, but it has been found that with a controlled uniform speed of movement, the same pressure is applied throughout substantially the entire crushing operation, and this pressure may be made light enough so that a destructive pressure is not applied to the grinding wheel, and is strong enough to insure the crusher rotation at substantially the same peripheral speed as the grinding wheel so that no grinding operation takes place on the grinding wheel itself during the crushing.

While the form of apparatus herein illustrated and described constitutes a preferred embodiment of the invention, it is to be understood that various modifications and adaptations of the invention may be made without departing from the spirit and scope of the invention which is defined in the appended claims.

What is claimed is:

1. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, drive means for driving said grinding wheel comparatively slowly in a forming operation on the grinding wheel, a rotatable crusher for dressing the grinding wheel, means manually operable to bodily adjust the crusher from a remote position into peripheral contact with the grinding wheel, switch means under the control of the operator, a motor controlled by said switch means and having a drive shaft and a threaded feed member mechanically connected to said shaft for positively moving the crusher axis toward the grinding wheel axis at a uniform rate of speed irrespective of any eccentricity of the grinding wheel.

2. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, drive means for rotating said grinding wheel comparatively slowly in a forming operation on the grinding wheel, a rotatable crusher for dressing the grinding wheel, a positive stop, means manually operable to bodily adjust the crusher from a remote position to a position limited by said stop, switch means under the control of the operator, an electric motor controlled by said switch means, and adjusting mechanism mechanically driven by said motor in timed relation with said motor for positively slowly feeding the crusher bodily toward the grinding wheel axis at a uniform rate of speed.

3. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, drive means for driving said grinding wheel comparatively slowly in a forming operation on the grinding wheel, a rotatable crusher for dressing the grinding wheel, a crusher holder for the crusher, a slidable carrier, an adjusting motor including a motor shaft, means driven by said motor and mechanically interconnecting the motor shaft to said holder for positively moving the holder on the carrier at a uniform rate of speed, and means for manually adjusting the slidable carrier from a position in which the crusher is remote from the grinding wheel to a definite predetermined position, and stop means for determining said predetermined position of the carrier.

4. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, drive means for driving said grinding wheel comparatively slowly in a forming operation on the grinding wheel, a rotatable crusher for dressing the grinding wheel, means manually operable to bodily adjust the crusher from a remote position into peripheral contact with the grinding wheel, switch means under the control of the operator, a motor controlled by said switch means, adjusting mechanism driven by said motor for moving the crusher towards the grinding wheel axis at a uniform rate of speed, and timing means to deenergize the motor during the continued operation of the said drive means.

5. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, a crusher, a holder for said crusher, a slidable carrier, a motor driven feed screw mechanism for positively adjusting the holder on the carrier at a uniform rate of speed to feed the crusher slowly toward the grinding wheel axis, a carrier support, manually operable means for adjusting the carrier on said support to advance the crusher to the grinding wheel, means for fixing the carrier on the carrier support, and means for driving said grinding wheel comparatively slowly in a forming operation on the grinding wheel.

6. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, a crusher, a holder for said crusher, a slidable carrier, motor driven mechanism for adjusting the holder on the carrier at a uniform rate of speed to feed the crusher slowly toward the grinding wheel axis, a carrier support, manually operable means for adjusting the carrier on said support, means for fixing the carrier on the carrier support, drive means for driving said grinding wheel comparatively slowly in a forming operation on the grinding wheel, mean-s for automatically timing the operation of said drive means, and indicating means showing the position of the crusher with respect to the carrier.

7. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, drive means for driving said grinding wheel comparatively slowly in forming operation on the grinding wheel, a rotatable crusher for dressing the grinding wheel, a crusher holder for the crusher, an adjustable slide, a slide support, means for manually controlling the position of the slide on said support, stop means limiting movement of the slide in one direction, looking means for holding the slide in an adjusted position on the support, a, threaded shaft for adjusting the crusher holder along the slide, means for manually controlling said shaft, an adjusting motor carried by the crusher holder, drive means connecting said motor to said shaft to adjust said holder at a uniform rate of speed during motor operation, and means controlling operation of said motor.

8. A grinding machine having a grinding wheel operable at comparatively high speed in a grinding operation, drive means for driving said grinding wheel comparatively slowly in a forming operation on the grinding wheel, a rotatable crusher for dressing the grinding wheel, a crusher holder for the crusher, means manually operable to adjust the crusher holder from a remote position into a position in which the crusher is in pressure contact with the grinding wheel, switch means under the control of the operator, a motor controlled by said switch means, adjusting mechanism driven by said motor for moving the crusher holder toward the grinding wheel at a uniform rate of speed, an adjustable timing means for controlling time duration of motor operation, and means operable in timed relation with the starting and stopping of said motor to control said drive means.

LOUIS F. POLK.

REFERENCES CITED UNITED STATES PATENTS Name Date Wickman June 9, 1942 Number 

